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Near-field radiative heat transfer (NFRHT) arises between objects separated by nanoscale gaps and leads to dramatic enhancements in heat transfer rates compared to the far-field. Recent experiments have provided first insights into these enhancements, especially using silicon dioxide (SiO2) surfaces, which support surface phonon polaritons (SPhP). Yet, theoretical analysis suggests that SPhPs in SiO2occur at frequencies far higher than optimal. Here, we first show theoretically that SPhP-mediated NFRHT, at room temperature, can be 5-fold larger than that of SiO2, for materials that support SPhPs closer to an optimal frequency of 67 meV. Next, we experimentally demonstrate that MgF2and Al2O3closely approach this limit. Specifically, we demonstrate that near-field thermal conductance between MgF2plates separated by 50 nm approaches within nearly 50% of the global SPhP bound. These findings lay the foundation for exploring the limits to radiative heat transfer rates at the nanoscale.

Background: Observational studies and randomized controlled trials have yielded inconsistent findings about the association between the use of acid-suppressive drugs and the risk of pneumonia. We performed a systematic review and meta-analysis to summarize this association. Methods: We searched three electronic databases (MEDLINE [PubMed], Embase and the Cochrane Library) from inception to Aug. 28, 2009. Two evaluators independently extracted data. Because of heterogeneity, we used random-effects meta-analysis to obtain pooled estimates of effect. Results: We identified 31 studies: five case-control studies, three cohort studies and 23 randomized controlled trials. A meta-analysis of the eight observational studies showed that the overall risk of pneumonia was higher among people using proton pump inhibitors (adjusted odds ratio [OR] 1.27, 95% confidence interval [CI] 1.11-1.46, [I.sup.2] 90.5%) and [histamine.sub.2] receptor antagonists (adjusted OR 1.22, 95% CI 1.09-1.36, [I.sup.2] 0.0%). In the randomized controlled trials, use of [histamine.sub.2] receptor antagonists was associated with an elevated risk of hospital-acquired pneumonia (relative risk 1.22, 95% CI 1.01-1.48, [I.sup.2] 30.6%). Interpretation: Use of a proton pump inhibitor or [histamine.sub.2] receptor antagonist may be associated with an increased risk of both community- and hospital-acquired pneumonia. Given these potential adverse effects, clinicians should use caution in prescribing acid-suppressive drugs for patients at risk., Recently, the medical literature has paid considerable attention to unrecognized adverse effects of commonly used medications and their potential public health impact. (1) One group of medications in widespread use [...]

Quantitative mapping of temperature fields with nanometric resolution is critical in various areas of scientific research and emerging technology, such as nanoelectronics, surface chemistry, plasmonic devices, and quantum systems. A key challenge in achieving quantitative thermal imaging with scanning thermal microscopy (SThM) is the lack of knowledge of the tip–sample thermal resistance (RTS), which varies with local topography and is critical for quantifying the sample temperature. Recent advances in SThM have enabled simultaneous quantification of RTSand topography in situations where the temperature field is modulated enabling quantitative thermometry even when topographical features cause significant variations in RTS. However, such an approach is not applicable to situations where the temperature modulation of the device is not readily possible. Here we show, using custom-fabricated scanning thermal probes (STPs) with a sharp tip (radius ∼25 nm) and an integrated heater/thermometer, that one can quantitatively map unmodulated temperature fields, in a single scan, with ∼7 nm spatial resolution and ∼50 mK temperature resolution in a bandwidth of 1 Hz. This is accomplished by introducing a modulated heat input to the STP and measuring the AC and DC responses of the probe’s temperature which allow for simultaneous mapping of the tip–sample thermal resistance and sample surface temperature. The approach presented here─contact resistance resolved scanning thermal microscopy (CR-SThM)─can greatly facilitate temperature mapping of a variety of microdevices under practical operating conditions.

In this study, we demonstrate a viable and promising optical engineering technique enabling the development of high-performance plasmonic organic photovoltaic devices. Laser interference lithography was explored to fabricate metal nanodot (MND) arrays with elaborately controlled dot size as well as periodicity, allowing spectral overlap between the absorption range of the active layers and the surface plasmon band of MND arrays. MND arrays with ∼91 nm dot size and ∼202 nm periodicity embedded in a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) hole transport layer remarkably enhanced the average power conversion efficiency (PCE) from 7.52% up to 10.11%, representing one of the highest PCE and degree of enhancement (∼34.4%) levels compared to the pristine device among plasmonic organic photovoltaics reported to date. The plasmonic enhancement mechanism was investigated by both optical and electrical analyses using finite difference time domain simulation and conductive atomic force microscopy studies.

In this work, we developed the perovskite photodiodes based on the dimensionality-reduced quasi two-dimensional (Q-2D) photoactive layer structure by incorporating phenylethylammonium iodide (PEAI) into methylammonium lead iodide (MAPbI3), which effectively enhanced both the crystalline phase and the ambient stability of the perovskite. The Q-2D perovskite photodiode exhibited a dark current of 1.76 × 10−7A/cm2, resulting in the detectivity (D*) of 2.20 × 1012J and responsivity of 0.53 A/W, which is among the highest performance levels without the voltage bias (0 V) due to the systematically optimized perovskite phase resulting in the reduced leakage current. In addition, the current density of Q-2D perovskite photodiode maintained 76% of the initial level current density even after 80 days in the ambient condition, compared to 15% of 3D perovskite photodiode control sample. Such superior performance and stability were mainly attributed to the enhanced degree of crystallization of the Q-2D perovskites, which was confirmed by X-ray diffraction and grazing incidence wide-angle X-ray scattering (GIWAXS) measurement. Also, the improved stability of Q-2D perovskite films was confirmed by both lifetime test and atomic force microscopy studies where the negligible number of pinholes was observed in the quasi-2D perovskite films while considerable deformations were found in the 3D perovskites photodiode. Our study suggests a simple and robust protocol for the development of stable and high-performance perovskite photodetectors via dimensional and constitutional optimization of conventional perovskites for the practical usage of perovskite in the photodiode applications.

In recent years, the concept of combined therapy using gold hybrid nanomaterials has been broadly adopted to pioneer new anticancer treatments. However, their synergistic anticancer effects have yet to be thoroughly investigated. Herein,a hybrid gold nanobipyramid nanostructure coated with molybdenum disulfide (MoS2) semiconductor (AuNBPs@MoS2) was proposed as a smart nanozyme for anticancer therapy and two-photon bioimaging. The hybrid material showed dramatically enhanced localized surface plasmon resonance property under excitation owing to its anisotropic nature, coupled with the rich electron density in MoS2,resulting in the superior in situ photogeneration of reactive oxidative species (ROS - 1O2, •OH). We demonstrated that the synergistic effect of enhanced photothermal conversion and generation of ROS could increase the anticancer effect of AuNBPs@MoS2. Two-photon luminescence imaging confirmed that AuNBPs@MoS2was successfully internalized in cancer cells and that simultaneous anticancer treatments based on catalytic and photothermal therapy could be achieved. This study highlighted, for the first time, a novel approach of plasmon-mediated powerful anticancer therapy and imaging via the unprecedented combination of anisotropic AuNBPs and two-dimensional MoS2material.

Hybrid semiconductor/noble metal nanostructures coupled with responsive polymers were used to probe unique plasmon-mediated photocatalytic properties associated with swelling–shrinking transitions in polymer chains triggered by specific external stimuli. Poly(N-isopropylacrylamide) (PNIPAM) brushes were anchored on Au films by atom transfer radical polymerization and ZnO nanoparticles were immobilized on the PNIPAM layer to explore controlled photocatalytic activity. The plasmon-enhanced photocatalytic activity was dictated by two critical parameters, that is, grafting density and molecular weight of PNIPAM involved in Au film-PNIPAM-ZnO. The effect of the areal density of PNIPAM chains on the temperature-responsive UV light photocatalytic activities showed mutually antagonistic trends at two different temperatures. The performance at high density was higher above a lower critical solution temperature (LCST), that is, under contracted configuration, while the sample with low density showed higher activity below LCST, that is, extended configuration. Among all the cases explored, the UV light activity was highest for the sample with thin PNIPAM layer and high density above LCST. The visible light activity was induced only for thin PNIPAM layer and high density, and it was higher above LCST. The efficiency of photocatalytic decomposition of phenol pollutant was dramatically enhanced from 10% to 55% upon the increase in temperature under visible light illumination.

Indoor lighting-driven photovoltaic cells have significant potential for energy generation due to their ability to convert waste lighting into reusable sources and energy generation regardless of weather conditions. As a promising renewable source of energy, indoor perovskite photovoltaic cells possess the advantages of high efficiency, facile processability, and cost-effectiveness. Here, we propose stoichiometry-controlled perovskite-based photovoltaic cells illuminated under the dim light-emitting diode (LED) to capture and recycle the light sources. Among the various stoichiometric methods tested, 10% bromide-doped perovskite photoactive layers exhibit the best performance as a result of better crystallization and uniform surface. This helps to form larger grains of perovskite with reduced trap sites and defects, which suppresses carrier trapping and non-radiation recombination centers, resulting in improved device performance. Moreover, additional substitution by an appropriate halide increases the stability of the conventional perovskite by forming a pseudo-cubic phase. Consequently, the photovoltaic device examined under dim LED (1000 lx) indoor lighting exhibits an average power conversion efficiency of 34.5 ± 1.2%, which is superior by 18% compared with that of a control device (29.2 ± 1.6%). These results reveal the potential of indoor-driven perovskite photovoltaic cells as next-generation power sources which may pioneer the development of new types of indoor electronics.